Fast evolving mobile communication technologies make it possible to enjoy high quality Guaranteed Bit Rate (GBR) services via a wireless connection even when users are moving. For example, users may listen to pop music that are downloaded from Internet when driving a car, or watch high-resolution TV from the web in a long-distance bus. Another example is that users can check the live video of home environments with mobile terminal in a bus.
When a user is stationary it is relatively easy to guarantee a Quality of Service (QoS) for GBR services, as long as the cell load is not too high, above some value. However, it becomes more difficult to achieve the high perceptional quality for a user when the user moves. The more a GBR user move, the more difficulties there will be to maintain the QoS for the GBR user due to handover and different load conditions in a new cell.
A conventional solution to guarantee QoS for a GBR user include priority-based scheduling policies, for example, the so-called delay scheduler which may take into account the packet delay and radio channel quality when scheduling packet transmission. A conventional solution can also include admission control (AC) or congestion control (CC), or some resource consumption limitation policies. These schemes are often used when the system is overloaded. In such a scenario, the resources will be mostly utilized for higher priority services because the system has scarce resources. It is also possible for the system to apply other types QoS schemes to guarantee the GBR users satisfied at higher probability. One example is that the GBR users may have different Handover (HO) triggering settings than the other users.
All above described schemes are designed mainly to enhance the system performance, for examples, increase the system capacity or coverage. However, the user performance metrics that are usually considered by the schemes are not enough. Thus, using conventional methods, the system sometimes may have to sacrifice some users so that those users will be badly serviced, in order to guarantee a good overall system performance.
Another problem is that existing methods for providing a guaranteed QoS are usually designed for a case where the users are slowly moving. This implies that the schemes may not work well in a case, where users have more mobility.
In short, mobility user using a GBR service may encounter several interruptions due to handover and even relatively long interruptions since some cells are very high loaded or have bad coverage.
Hence there exist a need for new methods and devices providing improved performance in cellular radio systems providing GBR services.